Despite their remoteness, polar regions are reached by pollutants emitted at lower latitudes due to long-range transport mechanisms. Pollution events can also occur at local scale following increasing research and tourism activities. Sponges are extremely efficient filter feeders. This ability makes them excellent accumulation systems and important sentinels for pollution, also in remote areas. Sponges also represent important habitats for a community of associated (micro)organisms, and investigations on Antarctic sponge-associated bacteria are increasing in the last years. To find a glue between pollution level and bacterial communities in sponge mesohyl, this work aims at both investigating pollutant (i.e., polycyclic aromatic hydrocarbons, PAHs, polychlorinated biphenyls, PCBs, and heavy metals, HM) concentration by chemical analyses and estimating microbial community taxonomic composition by 16S rRNA gene metabarcoding approach in two Antarctic sponge species, i.e. Haliclona (Rhizoniera) dancoi (Topsent, 1901) and Haliclona scotti (Kirkpatrick, 1907) inhabiting two sites within the Thetys Bay (Terra Nova Bay, Ross Sea). Abiotic matrices (i.e., water and sediment) were also analyzed. Some HMs (e.g., Hg, Ni, Zn and Cd), almost all tested PAHs and PCB congeners were more concentrated in the sponge mesohyl than in sediment. The associated bacterial community was dominated by bacterial phyla frequently found in marine environments of polar regions, but the diversity indices highlighted a higher alpha-diversity compared with previous studies. Distinct bacterial communities occurred in the biotic and abiotic investigated matrices, suggesting a high specificity of the sponge-associated communities. Actinomycetota, Acidobacteriota, Planctomyceota, and Bacteroidota were negatively correlated with low chlorinated PCBs. Obtained results suggest that Antarctic sponges could be an excellent sentinel of environmental pollution and that differences among the bacterial communities may be site-driven and dependent on relationships between bacteria and pollutants concentration in the benthic hosts.
Antarctic sponges Haliclona (Rhizoniera) dancoi (Topsent, 1901) and Haliclona scotti (Kirkpatrick, 1907) from the Thetys Bay (Terra Nova Bay, Antarctica): associated bacterial communities vs pollutant accumulation
Bertolino M.;
2023-01-01
Abstract
Despite their remoteness, polar regions are reached by pollutants emitted at lower latitudes due to long-range transport mechanisms. Pollution events can also occur at local scale following increasing research and tourism activities. Sponges are extremely efficient filter feeders. This ability makes them excellent accumulation systems and important sentinels for pollution, also in remote areas. Sponges also represent important habitats for a community of associated (micro)organisms, and investigations on Antarctic sponge-associated bacteria are increasing in the last years. To find a glue between pollution level and bacterial communities in sponge mesohyl, this work aims at both investigating pollutant (i.e., polycyclic aromatic hydrocarbons, PAHs, polychlorinated biphenyls, PCBs, and heavy metals, HM) concentration by chemical analyses and estimating microbial community taxonomic composition by 16S rRNA gene metabarcoding approach in two Antarctic sponge species, i.e. Haliclona (Rhizoniera) dancoi (Topsent, 1901) and Haliclona scotti (Kirkpatrick, 1907) inhabiting two sites within the Thetys Bay (Terra Nova Bay, Ross Sea). Abiotic matrices (i.e., water and sediment) were also analyzed. Some HMs (e.g., Hg, Ni, Zn and Cd), almost all tested PAHs and PCB congeners were more concentrated in the sponge mesohyl than in sediment. The associated bacterial community was dominated by bacterial phyla frequently found in marine environments of polar regions, but the diversity indices highlighted a higher alpha-diversity compared with previous studies. Distinct bacterial communities occurred in the biotic and abiotic investigated matrices, suggesting a high specificity of the sponge-associated communities. Actinomycetota, Acidobacteriota, Planctomyceota, and Bacteroidota were negatively correlated with low chlorinated PCBs. Obtained results suggest that Antarctic sponges could be an excellent sentinel of environmental pollution and that differences among the bacterial communities may be site-driven and dependent on relationships between bacteria and pollutants concentration in the benthic hosts.
I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
